Unitized radial fluid seal

ABSTRACT

A unitized radial fluid seal includes a shell having a first elastomeric seal body affixed thereto and defining a primary seal lip. A sleeve includes a substantially cylindrical, axially-extending sealing flange and a protective flange extending substantially radially from the axially-extending sealing flange. A spring radially urges the primary seal lip into sealing contact with a sealing surface of the axially-extending sealing flange. A second elastomeric seal body is affixed to the sleeve and includes a resiliently-elastic angled lip extending from a terminal end of the axially-extending sealing flange opposite of the radially-extending protective flange. The sealing surface and an axially-outward facing surface of the angled lip define an angle (α) that is between about 130-170°. The primary seal lip is axially retained between the angled lip and the radially-extending protective flange.

TECHNICAL FIELD

The present invention generally relates to a unitized radial fluid seal,preferably for retaining lubricant in and around a bearing, such as awheel bearing for a truck or other heavy-duty commercial vehicle.

KNOWN ART

Unitized radial shaft seals are utilized in the vehicle field to protectwheel bearings by providing a barrier between a rotatable wheel hub anda stationary wheel spindle or shaft. Such wheel bearings requirecontinuous lubrication to reduce friction during operation.

The Scotseal® PlusXL wheel shaft seal, available from SKF USA, Inc. forseveral years, has been successfully employed as a unitized radial fluidseal for heavy duty applications, such as trucks and buses. In additionto retaining lubricant around the wheel bearings, it also effectivelyprevents contamination, such as dirt and water, from reaching the wheelbearings.

An example of the known Scotseal® PlusXL is shown in FIG. 1 and itincludes two basic annular components, the outer shell or case 1 and theinner shell or sleeve 20.

The outer shell 1 includes a substantially L-shaped metal reinforcement2 and an elastomeric sealing element 3 made of a hydrogenated nitrilebutadiene rubber. The elastomeric sealing element 3 includes a primaryseal lip 4, a radial dust/dirt lip 5, an annular dust/dirt lip 6 and anouter bump lip 7, all of which are elastic and contact a surface of themetal sleeve 20 during operation. The primary seal lip 4 serves toretain the lubricant around the wheel bearings and the other three lips5, 6 and 7 serve to prevent contamination from entering into thelubrication chamber (sealed region). A plurality of annular beads 8 aredefined on the outside diameter (outside circumferential surface) of theelastomeric sealing element 3 for sealingly abutting against an adjacentsurface of the wheel hub.

A garter (annular coiled wire) spring 9 serves to radially-inwardly biasor load the primary seal lip 4 into sealing contact with the metalsleeve 20.

An elastomeric seal 21 is affixed to the substantially L-shaped metalsleeve 20 and is comprised of a blend of nitrile rubber and ethylenepropylene diene monomer rubber (EPDM rubber). A plurality of annularbeads 22 are defined on the inside diameter (inside circumferentialsurface) of the elastomeric seal 21 for sealingly abutting against afacing surface of the wheel spindle. A metal curl 23 extends from theterminal end of the sleeve 20 that is closest to the wheel bearings andserves as a collar or rim to retain the outer shell 1 in a unitizedmanner with the sleeve 20. Further teachings concerning the curl 23 maybe found in U.S. Pat. No. 4,531,748.

The primary seal lip 4 has a Wave® seal lip construction, which reducesfriction and thus heat generation while also serving to pump thelubricant back towards the wheel bearings and push dirt away from thelubrication chamber. For this purpose, the primary seal lip is a smoothlip, bi-rotational hydrodynamic radial lip seal formed in a sinusoidalor wave pattern. This design also reduces shaft wear and increasesservice life, while not losing pumping power as it wears.

In addition, U.S. Pat. No. 5,186,472 discloses a unitized radial shaftseal that includes a cylindrical outer covering or case made of sheetsteel (shell) having an elastomeric outer ring affixed thereto forsealing against a housing bore. An elastomeric seal lip extends from theshell and provides a dynamic and static seal against the inner casing orsleeve. A garter spring is provided to elastically urge or bias the seallip into sealing contact with the opposing surface. The inner casing orsleeve is mounted on the rotary shaft and includes a radially-extendingportion that curls around the seal lip.

Other unitized fluid seals are disclosed in U.S. Pat. Nos. 6,471,211 and4,448,426.

SUMMARY

While the unitized fluid seal 1 shown in FIG. 1 has been verysuccessful, two disadvantages have been identified.

First, during installation, maintenance or removal of the fluid seal 1of FIG. 1, the metal curl 23 can come into contact with the sealing lip4, thereby compromising or damaging the functional integrity of thesealing lip 4. This damage may lead to premature failure of the fluidseal 1 or may limit the opportunity to identify the root cause of theseal failure for a fluid seal known to be at the end of its servicelife.

Second, the fluid seal 1 of FIG. 1 is typically manufactured by placingthe outer shell 1 adjacent to the sleeve 20 and then radially-outwardlycurling the terminal end (skirt portion) of the sleeve 20 using aclosing die in order to form the curl 23 and thereby retain the outershell 1 between the curl 23 and the radially-extending flange of thesleeve 20. Thus, an extra manufacturing step is required to unitize theouter shell 1 and sleeve 20 and moreover, a sharp edge may be formed onthe curl 23 by the closing die. The sharp edge on the curl 23 willlikely cause damage to the relatively soft sealing lip 4 if the twoparts come into contact.

Therefore, it is an object of the present teachings to provide animproved unitized radial fluid seal, which preferably overcomes one ormore problems of the known art.

In a first aspect of the present teachings, a unitized radial fluid sealmay include a shell comprising a substantially cylindrical,axially-extending first flange and a second flange extendingsubstantially radially from the axially-extending first flange. A firstelastomeric seal body may be affixed to the shell and may comprise acircumferentially-extending primary seal lip, e.g., an annular lip sealor a sinusoidal or wave-like lip seal. A sleeve may comprise asubstantially cylindrical, axially-extending sealing flange and aprotective flange extending substantially radially from theaxially-extending sealing flange. A spring may radially urge the primaryseal lip into sealing contact with a sealing surface of theaxially-extending sealing flange. A second elastomeric seal body may beaffixed to the sleeve and may include a resiliently-elastic angled lipextending from a terminal end of the axially-extending sealing flangeopposite of the radially-extending protective flange. A first angle (α)defined by the sealing surface and an axially-outward facing surface ofthe angled lip is preferably between about 130-170° and the primary seallip is axially retained between the angled lip and theradially-extending protective flange.

In a further aspect of the present teachings, the first angle (α) ispreferably between about 140-180° or more preferably between about155-165°. An angled lip according to these aspects of the presentteachings provide an advantageous balance between axial retention of theprimary seal lip and prevention of damage to the primary seal lip duringinstallation, maintenance or removal of the unitized radial fluid seal.

In addition or in the alternative, an axially-inward facing surface maybe defined on the angled lip and a second angle (β) defined by theaxially-inward facing surface of the angled lip and the radial directionis preferably between about 40-80°, more preferably between about50-70°, even more preferably between about 55-65°.

In addition or in the alternative, a radially-inward, angled surface maybe defined on the angled lip and a third angle (y) defined by theradially-inward, angled surface and the axial direction is preferablybetween about 20-60°, more preferably between about 25-45°, morepreferably between about 30-35°.

In addition or in the alternative, the spring may be an annular coiledwire spring, e.g., a garter spring.

In addition or in the alternative, the first elastomeric seal body mayfurther include one or more of an annular dust seal, a radial dust sealand an outer bump seal, each contacting the sleeve.

In addition or in the alternative, the first elastomeric seal body mayfurther include an outside diameter mounting portion defining aplurality of annular beads and/or the second elastomeric seal body mayfurther include an inside diameter mounting portion defining a pluralityof annular beads.

Further features, objects and advantages of the present teachings willbecome apparent after reading the following detailed description andclaims in view of the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a known unitized fluid seal.

FIG. 2 shows a unitized fluid seal according to the present teachings.

DETAILED DESCRIPTION OF THE INVENTION

The representative fluid seal disclosed below includes a sleeveconfigured to be mounted or seated on a shaft or other cylindricalmachine part and a primary sealing lip is disposed radially outwardlythereof. However, it should be understood that the present teachingsapply equally to fluid seals wherein these parts are reversed. In suchcase, the seal band of the primary seal unit may be urged radiallyoutwardly against a seal companion flange or unitizing element which isdisposed radially outwardly of the primary seal.

Furthermore, it should also be understood that various elastomers areuseful in making the present fluid seal, including elastomers,fluorocarbons or other lubricous resinous materials. Thus, the presentteachings are not intended to be limited to the use of any particularmaterial, except insofar as such material would not be suitable for usein a fluid seal of the type encompassed by the present teachings.

As used in the present description, the expression “assembled”, or wordsof similar meaning, should be understood to be synonymous with“unitized” as meaning a seal having two elements which are, afterassembly, held or retained together for cooperative sealing action. Insuch a seal, the entire assembly includes two major or primary partswhich rotate relative to each other, with a primary seal band area beingformed as a seal lip or the like on one part, and a sleeve surface beingformed on the other part. In other instances, not dealt with here, theexpression “assembled” is sometimes understood to mean seals in whichthe primary seal element itself, i.e. an element containing both acasing and a body having a primary seal band thereon, are assembled byclamping, clinching, or the like rather than bonding. In the presentdescription, the expression “assembled” is to be understood as beingsynonymous with unitizing and not as implying that the attachment of theprimary seal body to its associated mounting flange is done by crimpingor clamping.

Referring now to FIG. 2, a representative unitized radial fluid seal isshown and denoted as a whole with 100. Such a fluid seal 100 may beinstalled within a machine assembly in order to seal an opening betweenrotating and non-rotating structures, e.g., to seal a lubricant around abearing. In a particularly preferred application of the presentteachings, the seal 100 is disposed between a wheel spindle and a wheelhub of a vehicle, such as a truck, bus or other heavy-duty commercialvehicle, although the present teachings are certainly not limited tosuch applications.

The seal 100 includes two principal components, namely a seal elementgenerally designated with 110 and a sleeve element generally designatedwith 150.

The seal element 110 includes an outer shell or case 112 having anaxially-extending, substantially-cylindrical mounting flange 114 and aradially-inward extending flange 116. The outer shell 112 is preferablymade of a rigid, durable material, such as steel or another metallicmaterial. However, hard plastics also may be employed to form the outershell 112.

According to conventional terminology, the side of the seal 100 lying tothe right in FIG. 2 is known as the “fluid side” of the seal 100,whereas the portion of the seal lying to the left is referred to as the“air side”. Accordingly, in FIG. 2 the region indicated by 102 is theenclosed or sealed region, while the region indicated by 104 liesoutside the sealed region. Consequently, as used herein, the expression“axially inner” means toward the fluid side 102 of the seal 100 ortoward the interior of the sealed region, whereas “axially outer” refersto the portion 104 of the seal 100 directed or lying toward the exteriorof the sealed region.

The outer shell 112 is at least partially embedded in an elastomericseal body generally designated with 120. The seal body 120 includesinner portion 122 disposed on the radially-inward side of the outershell 112 and an exterior, mounting portion 124. A radial force-applyingprimary seal body 126 extends from the inner portion 122 and includes aprimary seal lip or ring 128. In the annular or circumferentialdirection of the seal body 126, the primary seal lip 128 may extendeither in a circular manner or in a sinusoidal (or wave-like) manner.

The entire elastomeric seal body 120 may preferably be integrally formedfrom a single elastomeric material, such as e.g., nitrile butadienerubber (NBR) or hydrogenated nitrile butadiene rubber (HNBR). In thealternative, the elastomeric seal body 120 may be a composite componentwith two portions formed from different materials. The skilled personwill recognize that a wide variety of elastomeric materials, such asunsaturated and saturated rubbers, may be used in accordance with thepresent teachings, as well as fluorocarbon materials such aspolytetrafluoroethylene. Blended sealing materials known in the art alsomay be utilized to form the seal body 120 in whole or at least in part.

The elastomeric seal body 120 may completely surround or encapsulate theouter shell 112 or one or more portions of the outer shell 112 may beexposed.

A plurality of annular mounting ribs or beads 125 preferably extendcircumferentially around the elastomeric mounting portion 124 and serveto sealingly abut an adjacent machine part, such as a surface of a wheelhub.

An annular dirt/dust lip 130, a radial dirt/dust lip 132 and an outerbump lip 134 are also defined on the elastomeric seal body 120 and serveto prevent ingress of contamination from the exterior, air side 104 intothe fluid side 102 or sealed region.

An annular spring groove 136 is defined in the primary seal body 126 andaccommodates an annular coiled wire (garter) spring 138, which applies aradially-inward directed force to urge the primary seal lip 128 intoannular contact with the adjacent radially-outward surface 154 of thesleeve 150.

The sleeve 150 is preferably comprised of a durable, rigid material,such as steel or another metallic material, although again durable,rigid plastics may be used in certain applications. The sleeve 150includes a central, generally cylindrical, axially-extending sleeveportion 152 having a radially-outwardly directed primary sealing surface154 designed to contact the primary seal lip 128 and the annular dirtlip 130 during operation of the fluid seal 100.

The axially outermost portion of the sleeve 150 includes aradially-outwardly extending protective flange 156 having an end portion158 with an outside diameter that is slightly less than the outsidediameter of the elastomeric mounting portion 124. In use, the radialdirt lip 132 and outer bump lip 134 are designed to contact aradially-extending surface 160 and thereby serve as the first barrier toprevent ingress of dirt, water or other types of contamination from theair side 104.

An inner seal body 170 is fixedly attached to the radially-inward sideof the sleeve 150 and includes a plurality of annular mounting ribs orbeads 172 for sealingly abutting on a machine part, such as a wheelspindle.

The inner seal body 170 further includes an over-molded portion orangled lip 174, which extends from the terminal end of the sleeve 150generally in the axial direction towards the fluid side 102. The innerseal body 170 and angled lip 174 encompass an embedded flange orradially-inward directed curl 153 defined on the sleeve 150.

An axially-outward facing surface 176 of the lip 174 extends from thecurl 153 at an angle (α) to the primary sealing surface 154 of betweenabout 130-170°, more preferably between about 140-180° and mostpreferably about 155-165°. An axially-inward facing surface 178 of theangled lip 174 preferably extends at an angle (β) to the radialdirection (indicated by the vertical dot-dash line) of between about40-80°, more preferably between about 50-70° and most preferably betweenabout 55-65°. A radially-inward, angled surface 180 preferably extendsat an angle (y) to the axial direction (indicated by the horizontaldashed line) of between about 20-60°, more preferably between about25-45° and most preferably between about 30-35°.

The angled lip 174 preferably has a thickness in the radial direction ofabout 2-4 mm, although the thickness will depend upon the particularapplication and the overall size of the fluid seal 100.

The inner seal body 170 may be made of a variety of elastomericmaterials, such as unsaturated rubbers, e.g., nitrile rubber (NBR), andsaturated rubbers, e.g., ethylene propylene diene monomer (EPDM) rubber,or blends thereof.

The angled lip 174 is preferably constructed such that it is elasticallyand resiliently flexible and provides a semi-unitizing feature. That is,the angled lip 174 at least partially functions to retain the sealingelement 110 in the axial direction between the flange 156 and the angledlip 174 during storage and operation, thereby providing a unitized fluidseal 100. However, the angled lip 174 also allows the unitized fluidseal 100 to be assembled during manufacture by pushing the sealingelement 110 over the angled lip 174 in the axial direction withoutdamaging the primary seal lip 128 or more generally the primary sealbody 126.

Furthermore, even in the event that the primary seal body 126 or theprimary seal lip 128 comes into contact with the angled lip 174 duringinstallation, maintenance or removal of the fluid seal 100, the primaryseal body 126 or the primary seal lip 128 will not be damaged, therebyprotecting the integrity of the primary seal body 126 and the primaryseal lip 128.

A representative, non-limiting example of the present invention wasdescribed above in detail with reference to the attached drawings. Thisdetailed description is merely intended to teach a person of skill inthe art further details for practicing preferred aspects of the presentteachings and is not intended to limit the scope of the invention.Furthermore, each of the additional features and teachings disclosedabove may be utilized separately or in conjunction with other featuresand teachings to provide improved unitized fluid seals and methods formanufacturing the same.

Moreover, combinations of features and steps disclosed in the abovedetail description may not be necessary to practice the invention in thebroadest sense, and are instead taught merely to particularly describe arepresentative example of the invention. Furthermore, various featuresof the above-described representative example, as well as the variousindependent and dependent claims below, may be combined in ways that arenot specifically and explicitly enumerated in order to provideadditional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intendedto be disclosed separately and independently from each other for thepurpose of original written disclosure, as well as for the purpose ofrestricting the claimed subject matter, independent of the compositionsof the features in the embodiments and/or the claims. In addition, allvalue ranges or indications of groups of entities are intended todisclose every possible intermediate value or intermediate entity forthe purpose of original written disclosure, as well as for the purposeof restricting the claimed subject matter.

REFERENCE NUMBER LIST

-   1 Outer shell-   2 Metal reinforcement-   3 Elastomeric sealing element-   4 Primary seal lip-   5 Radial dirt lip-   6 Annular dirt lip-   7 Outer bump lip-   8 Annular beads-   9 Garter spring-   20 Metal sleeve-   21 Elastomeric seal-   22 Annular beads-   23 Metal curl-   100 Unitized fluid seal-   102 Fluid side-   104 Air side-   110 Seal element-   112 Outer shell-   114 Axially-extending flange-   116 Radially-extending flange-   120 Elastomeric seal body-   122 Inner portion-   124 Exterior, mounting portion-   125 Outer annular beads-   126 Primary seal body-   128 Primary seal lip-   130 Annular dirt lip-   132 Radial dirt lip-   134 Outer bump lip-   136 Spring groove-   138 Garter spring-   150 Sleeve-   152 Axially-extending portion-   153 Curl-   154 Primary sealing surface-   156 Protective flange-   158 End portion-   160 Radially-extending surface-   170 Inner seal body-   172 Inner annular beads-   174 Angled lip-   176 Axially-outward facing surface-   178 Axially-inward facing surface-   180 Radially-inward, angled surface

1. A unitized radial fluid seal including: a shell comprising asubstantially cylindrical, axially-extending first flange and a secondflange extending substantially radially from the axially-extending firstflange, a first elastomeric seal body affixed to the shell andcomprising a radially-extending primary seal lip, a sleeve comprising asubstantially cylindrical, axially-extending sealing flange and aprotective flange extending substantially radially from theaxially-extending sealing flange, a spring radially urging the primaryseal lip into sealing contact with a sealing surface of theaxially-extending sealing flange, and a second elastomeric seal bodyaffixed to the sleeve and including a resiliently-elastic angled lipextending from a terminal end of the axially-extending sealing flangeopposite of the radially-extending protective flange, wherein a firstangle (α) defined by the sealing surface and an adjacent axially-outwardfacing surface of the angled lip is between about 130-170° and theprimary seal lip is axially retained between the angled lip and theradially-extending protective flange.
 2. A unitized fluid seal accordingto claim 1, wherein the first angle (α) is between about 140-180°.
 3. Aunitized fluid seal according to claim 2, wherein the first angle (α) isbetween about 155-165°.
 4. A unitized fluid seal according to claim 3,wherein an axially-inward facing surface is defined on the angled lipadjacent the axially-outward facing surface and a second angle (β)defined by the axially-inward facing surface of the angled lip and theradial direction is between about 40-80°.
 5. A unitized fluid sealaccording to claim 4, wherein the second angle (β) is between about50-70°.
 6. A unitized fluid seal according to claim 5, wherein thesecond angle (β) is between about 55-65°.
 7. A unitized fluid sealaccording to claim 6, wherein a radially-inward, angled surface isdefined on the angled lip adjacent the axially-inward facing surface anda third angle (y) defined by the radially-inward, angled surface and theaxial direction is between about 20-60°.
 8. A unitized fluid sealaccording to claim 7, wherein the third angle (y) is between about25-45°.
 9. A unitized fluid seal according to claim 8, wherein the thirdangle (y) is between about 30-35°.
 10. A unitized fluid seal accordingto claim 9, wherein the spring is an annular coiled wire spring and thefirst elastomeric seal body further includes an annular dust seal, aradial dust seal and an outer bump seal, each contacting the sleeve. 11.A unitized fluid seal according to claim 10, wherein the firstelastomeric seal body further includes an outside diameter mountingportion defining a plurality of annular beads and the second elastomericseal body further includes an inside diameter mounting portion defininga plurality of annular beads.
 12. A unitized fluid seal according toclaim 1, wherein an axially-inward facing surface is defined on theangled lip and a second angle (β) defined by the axially-inward facingsurface of the angled lip and the radial direction is between about40-80°.
 13. A unitized fluid seal according to claim 12, wherein thesecond angle (β) is between about 50-70°.
 14. A unitized fluid sealaccording to claim 13, wherein the second angle (β) is between about55-65°.
 15. A unitized fluid seal according to claim 1, wherein aradially-inward, angled surface is defined on the angled lip and a thirdangle (y) defined by the radially-inward, angled surface and the axialdirection is between about 20-60°.
 16. A unitized fluid seal accordingto claim 15, wherein the third angle (y) is between about 25-45°.
 17. Aunitized fluid seal according to claim 16, wherein the third angle (y)is between about 30-35°.